This invention concerns an electromagnetic induction actuator to be mounted in small equipment such as portable telephones, pagers, other portable telecommunications equipment, wrist watches, toys and other small pieces of equipment. It also concerns such portable telephones, pagers and other portable telecommunications equipment.
Generally speaking, electromagnetic induction actuators have a round housing that encloses a diaphragm and a magnetic circuit that consists of a voice coil mounted on the inner surface of the diaphragm, a magnet for the magnetic circuit, a yoke that surrounds and supports the magnet, and a pole piece; there are also thin springs that support the magnetic circuit. The components are assembled with the springs fitted into the inner surface of the housing supporting the magnetic circuit, including the magnet, with the diaphragm fitted into an opening in the housing, and with a voice coil positioned close to the magnetic circuit.
This electromagnetic induction actuator is constituted with the magnetic circuit mounted so that it can move within the housing, by means of thin springs, so that structurally it has high impact resistance and resists breakage if dropped by the user.
This high impact resistance has been provided conventionally by means of projections that project from the inner wall of the housing and act as stoppers for the magnetic circuit (actually the outer perimeter of the yoke) if the magnetic circuit sways too far sideways on the spring. However, placing such projections on the inner wall of the housing requires that the diameter of the housing be made enough larger to allow for the projections, and so the overall dimensions of the actuator are increased.
Attempts have been made, for example, to place tabs at intervals around the periphery of the yoke to serve as impact resistance stoppers, rather than placing projections on the inner wall of the housing. Because the yoke is supported by springs, however, if tabs are formed on the yoke it is necessary to design and form the yoke itself so that the tabs will not contact the springs.
If the yoke itself is made thicker to separate the tabs from the spring in order to avoid contact between the tabs and the spring, the overall thickness of the actuator is increased, which obstructs miniaturization.
The purpose of this invention is to place tabs to serve as impact resistance stoppers while maintaining the small dimensions of the housing, and to make the actuator as a whole thinner and smaller, thus providing an electromagnetic induction actuator with good acoustical properties.
A further purpose of this invention is to provide an electromagnetic induction actuator that has an easily assembled structure, the structural parts of which can be easily and accurately positioned.
This invention also has the purpose of providing portable telecommunications equipment characterized by the incorporation of electromagnetic induction actuators with good acoustical properties.
In the electromagnetic induction actuator of this invention there is a round housing that encloses a diaphragm that transmits vibrations; a magnetic circuit that consists of a voice coil mounted on the inner surface of the diaphragm, a magnet for the magnetic circuit, a yoke that surrounds and supports the magnet, and a pole piece; and thin springs that support the magnetic circuit. The components are assembled with the springs fitted into the inner surface of the housing supporting the magnetic circuit, including the magnet, with the diaphragm fitted into an opening in the housing, and with a voice coil positioned close to the magnetic circuit. A number of tabs that act as shock resistance stoppers are located at equal intervals around the outer rim of the yoke and extend toward the inner surface of the wall of the housing. There is a spring that has an inner ring that fits the outer periphery of the yoke, an outer ring that fits the inner diameter of the housing, bridge arms that are spaced at equal distances around the circumference of the two rings and that connect the inner and outer rings, and recesses that are spaced at the same intervals as the bridge arms and that correspond to the positions of the tabs on the yoke. The yoke and spring together are assembled within the housing by positioning the tabs of the yoke in the recesses of the spring with the outer periphery of the yoke fitted into the inner diameter of the spring, and the outer ring of the spring fitted into the inner diameter of the housing.
The electromagnetic induction actuator of this invention can also be constituted with two springs of the same shape, a yoke having shock resistance stoppers in the form of L-shaped tabs that descend from its outer rim, and a stopper ring and ring washer that fit around the outer periphery of the yoke. The outer periphery of the yoke is fitted into the inner diameter of the 1st spring with the tabs of the yoke positioned inside the corresponding recesses on the 1st ring, and the stopper ring is fitted around the outer periphery of the yoke and presses against the inner ring of the spring. The tabs of the yoke are positioned corresponding to the recesses of the 2nd spring and the inner ring of the 2nd spring is fitted around the outer periphery of the yoke, contacting the stopper ring, and the ring washer is fitted around the outer periphery of the yoke and presses against the inner ring of the spring. The outer rings of the 1st and 2nd springs are fitted inside the inner diameter of the housing so that the yoke and springs are mounted together within the housing.
The electromagnetic induction actuator of this invention can also be constituted with a spacer ring sandwiched between the outer rings of the springs, and a cover that has a raised rim that fits inside the housing. The spacer ring is sandwiched between the outer rings of the springs, and the outer rings of the springs are fitted into the inside diameter of the housing; the outer ring of the 1st spring presses against the stop rim that is inside the housing near the opening, and the raised rim of the cover is fitted into an opening in the housing on the side opposite the diaphragm. The yoke and springs together are assembled within the housing by means of the raised rim of the cover pressing against the outer ring of the 2nd spring.
In the electromagnetic induction actuator of this invention there is a round housing that encloses a diaphragm that transmits vibrations; a magnetic circuit that consists of a voice coil mounted on the inner surface of the diaphragm, a magnet for the magnetic circuit, a yoke that surrounds and supports the magnet, and a pole piece; and thin springs that support the magnetic circuit. The components are assembled with the springs fitted into the inner surface of the housing supporting the magnetic circuit, including the magnet, with the diaphragm fitted into an opening in the housing, and with a voice coil positioned close to the magnetic circuit. There is a stopper ring that has a number of tabs that act as shock resistance stoppers located at equal intervals around its outer rim, extending toward the inner surface of the wall of the housing. There is a spring that has an inner ring that fits the outer periphery of the yoke, an outer ring that fits the inner diameter of the housing, bridge arms that are spaced at equal distances around the circumference of the two rings and that connect the inner and outer rings, and recesses that are spaced at the same intervals as the bridge arms and that correspond to the positions of the tabs on the stopper ring. The yoke and spring together are assembled within the housing by positioning the tabs of the stopper ring in the recesses of the spring with the inner ring of the spring pressed by fitting the stopper ring into the outer periphery of the yoke, and the outer ring of the spring fitted into the inner diameter of the housing.
It is also possible to constitute the electromagnetic induction actuator of this invention with two springs of the same shape, a stopper ring having shock resistance stoppers in the form of tabs that project from the outer periphery of the stopper ring, and a ring washer that fit around the outer periphery of the yoke. The outer periphery of the yoke is fitted into the inner ring of the 1st spring with the tabs of the stopper ring positioned inside the corresponding recesses on the 1st spring, and the stopper ring is fitted around the outer periphery of the yoke and presses against inner ring of the spring. The tabs of the stopper ring are positioned corresponding to the recesses of the 2nd spring and the inner ring of the 2nd spring is fitted around the outer periphery of the yoke, contacting the stopper ring, and the ring washer is fitted around the outer periphery of the yoke and presses against the inner ring of the spring. The outer rings of the 1st and 2nd springs are fitted inside the inner diameter of the housing so that the yoke and springs are mounted together within the housing.
Moreover, it is possible to constitute the electromagnetic induction actuator of this invention with a spacer ring sandwiched between the outer rings of the springs, and a cover that has a raised rim that fits inside the housing. The spacer ring is sandwiched between the outer rings of the springs, and the outer rings of the springs are fitted into the inside diameter of the housing; the outer ring of the 1st spring presses against the stop rim that is inside the housing near the opening, and the raised rim of the cover is fitted into an opening in the housing on the side opposite the diaphragm. The yoke and springs together are assembled within the housing by means of the raised rim of the cover pressing against the outer ring of the 2nd spring.
Further, it is possible to constitute the portable telecommunications equipment of this invention by incorporating within it any of the electromagnetic induction actuators described above.